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25 terms

The Universe

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photosphere
The inner layer of the Sun's atmosphere that gives off visible light; the Sun's surface.
corona
The outermost layer of the Sun's atmosphere.
core (of the sun)
The most central region of the Sun where nuclear reactions produce the Sun's energy. This is the most dense, and the hottest portion of the Sun.
radiative zone
The region of the Sun's interior that is outside of the core and in which energy moves by radiation.
convective zone
The region of the Sun where gases circulate in convection currents, bringing the Sun's energy to the surface.
fusion
Creation of energy by joining the nuclei of two lighter weight atoms to create one heavier atom (2 hydrogen atoms forming a single helium atom). This is the way stars produce energy.
sunspots
Areas on the Sun's surface that are cooler and less bright than surrounding areas. They are caused by the Sun's magnetic field, and occur in cycles
parallax
The apparent change in the position of a star in the sky due to the change in the Earth's position as the Earth moves around the sun. This always us to calculate the distance from Earth to the star.
absorption spectrum
A visual record of the wavelengths a particular star has absorbed. Certain elements will absorb certain wavelengths. This lets us figure out the elements that are part of that particular star.
Edwin Hubble
The scientist who came up with evidence for the Big Bang theory in the 1920s.
Hertzsprung-Russell diagram
A graph relating the surface temperatures and absolute brightnesses of stars.
red giant
A large, reddish star late in its life cycle; a star that expands and cools once it runs out of hydrogen fuel (this is what will happen to our sun).
supergiant
An extremely bright star of very large diameter and low density.
white dwarf
A former red giant star that has used up its helium and its outer layers escape into space, leaving behind a hot, dense core.
supernova
A massive explosion that occurs at the end of larger red giant stars life; the star releases large amounts of energy in all directions.
neutron star
A star that has collapsed under gravity to the point that the electrons and protons have smashed together to form neutrons. These stars are extremely dense and only about 12 miles across.
black hole
The final stage in the life cycle of a very massive star, where the core's mass collapses to a point that its gravity is so strong that not even light can escape.
Big Bang
The theory that the universe originated ~15 billion years ago from the cataclysmic explosion of a small mass of matter at extremely high density and temperature.
Big Freeze
One of the theories on how the universe will end, it states the universe will become a very cold, dark space as the stars cool and begin to burn out.
Big Crunch
One of the theories on how the universe will end, it states the universe will eventually collapse back in on itself when it is done expanding as a result of the Big Bang.
red shift
The apparent change in color of an object, caused by the change in the wavelength of light due to an object moving away from the observer.
Hubble's law
Proves that the universe is expanding. The farther a galaxy is, the faster it moves away from us. The greater the red shift (speed) the greater the distance.
constellation
A region of the sky that contains a recognizable star pattern and that is used to describe the location of objects in space
nebula
A cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter. Stars are formed here.
protostar
Earliest form of a star; This stage lies between the collapsing of dust and gas and the beginning of nuclear fusion.